You cannot reason anyone out of a position they did not reason themselves into.

I think it was not meant to convince anybody out of being flat-earther. It makes a fool out of them, but also it shows that there are humans behind the movement and their motivation (they went down the wrong path and got indoctrinated by the wrong people, and are now isolated by everybody else). I started the documentary thinking thar they are all stupid, and ended it feeling a bit sad about them and understanding a bit why would anybody continue to be part of a group spreating such an obvious lie. They really need some friends outside that group, support and some good education... the flat earthers and many conspiracy theory groups would have already died out, if society did not treat these people as a lost cause. It also explains indirectly why even some very intelligent people do fall for other conspiracy theories (like qanon).

I think it has changed how I would talk to a conspiracy theorist in real life, and I think it's great that it managed to do that.